Method and device for feeding molten resin, and method for manufacturing molded article by using the fed molten resin

ABSTRACT

A method and a device for feeding a molten resin capable of accurately feeding the molten resin without the delay of feed timing by preventing the molten resin from adhering to route members before it seats on a mold to increase the positioning accuracy of the molten metal in the mold, and a method of manufacturing a molded part by using the fed molten resin. Vibration is provided to the route members such as molten resin guide pins ( 10, 40, 50 ), throat members ( 62, 70, 85 ), and female mold positioned in a route in which the molten resin ( 25 ) passes before it seats on the female mold ( 7, 63 ) by a vibration imparting device ( 27 ) or a gas layer film is formed on the surfaces thereof. Thus, the molten resin can be fed while preventing it from adhering to the route members.

This application is a division of U.S. application Ser. No. 11/814,453,filed on Jul. 20, 2007, which is a 371 of PCT/JP2006/300697 filed onJan. 19, 2006, which is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 2005-014779, filed onJan. 21, 2005, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a method for feeding a molten resin toa molding apparatus that molds the molten resin, for example, when amolten resin extruded from a die head is fed to a mold and compressionmolded, and to a device for such feeding, and also to a method formanufacturing a molded article by using the fed molten resin.

BACKGROUND ART

A process in which a molten resin mass (referred to hereinbelow simplyas “molten resin”) extruded from a die head of an extruder is fed to amold and compression molded to the predetermined shape with a femalemold and a male mold has been widely used in the past. For example, inthe field of containers, the molten resin extruded from a die head iscompression molded in a mold as described hereinabove when molding apreform that is a premolded body for blow molding a synthetic resincontainer, molding a spout that is a discharge port of the container, ormolding a cap. In this case, accurately feeding and placing a moltenresin prior to compression molding to the desired position inside themold is a necessary condition for obtaining a good molded article. Theproblem is that the occurrence of displacement, oblique placing, orfalling delay causes molding defects. In particular, in the case of amultilayer molten resin that imparts a molded product with highfunctionality, if the molten resin is fed into a mold in an eccentric ortilted state and the compression molding is performed in this state,then the intermediate layers will shift to one side or the layers willbe ruptured, causing molding defects. For example, when a molded articleis obtained in which a multilayer resin comprises a gas barrier resinlayer inside thereof, the gas barrier layer can be exposed to theoutside or can be locally thinned or ruptured, whereby the gas barrierfunction will be lost.

A conventional molding apparatus has been suggested (see PatentDocument 1) in which a molten resin is extruded with an extruder, fed toa mold, and compression molded to obtain a compression molded product,this molding apparatus having a route by which the molten resin issupplied from a mold of the extruder to be placed into a mold of acompression molding machine, wherein the mold of the compression moldingmachine is located or passes directly below the die head of theextruder, an annular molten resin extruded from the die head is receivedby the surface of an intermediate support member that extends from themold of the compression molding machine and has an extending rod thatcan slide in the axial central section, and the molten resin is placedon the female mold by pushing down a molding plunger (male mold). In asuggested molding apparatus of another configuration (see PatentDocument 2), a die head of an extruder for a molten resin and a mold ofa compression molding machine are disposed so that the axial linesthereof are shifted from each other, a rotary disk is provided that hasa cutting-holding mechanisms disposed with a predetermined pitch on theouter peripheral section thereof, this mechanism conveying the moltenresin between the die head of the extruder and the mold of the moldingmachine, the cutting-holding mechanism conveys the molted resin todirectly above the mold by the rotation of the rotary disk, and moltenresin guiding means is provided so that it can be inserted between afemale mold and a male mold and removed therefrom.

-   Patent Document 1: Japanese Publication of Examined Application No.    07-61656-   Patent Document 2: Japanese Publication of Patent Application No.    2000-280248

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

As described hereinabove, a plurality of members (these members,including the female mold, will be generally referred to hereinbelow asroute members) are positioned for conveying or aligning and guiding themolten resin that was extruded from the die head of the extruder and cutto the predetermined length are disposed in a route leading to thefemale mold. Because the molten resin has an adhesive ability, themolten resin easily sticks or adheres (referred to hereinbelow simply as“adhesion”) to these members when it is brought into contact therewith.The resultant problems are as follows: the molten resin adheres to theroute members before the molten resin is seated on the bottom of thefemale mold, a free fall of the molten resin is inhibited, the moltenresin is seated in a tilted state, the falling timing thereof ischanged, the timing with the mold in which high-speed molding isperformed is changed, or the molten resin sticks permanently to theroute members and does not reach the female mold, causing moldingdefects, and the like. It is especially important to ensure accurateseating of the molten resin inside the mold in the contemporaryhigh-speed molding machines and in the manufacture of multilayer resinmolded articles.

Accordingly, it is an object of the present invention to provide amethod for feeding a molten resin that can reliably prevent a moltenresin from adhering to route members that are positioned in the routethereof when the molten resin is fed into a mold, increase the alignmentaccuracy of the molten resin inside the mold, ensure the accurate feedof the molten resin without a delay of feed timing or the like, andobtain good molded articles, and also to provide a device forimplementing such a method, and a method for manufacturing a moldedarticle from the molted resin that has been thus fed.

Means for Solving Problem

A method for feeding a molten resin in accordance with the presentinvention that resolves the above-described problems is a method forfeeding a molten resin by which a molten resin is fed to a moldingapparatus, wherein a route member, positioned in a route through whichthe molten resin passes prior to molding, is subjected to a molten resinadhesion preventing action by a molten resin adhesion preventing means,whereby the molten resin is fed to the molding apparatus, while beingprevented from adhering to the route member.

Imparting vibrations to the route member or forming an air layer on asurface of the route member can be advantageously employed as the moltenresin adhesion preventing means. A method by which the air layer isformed by directly feeding the air to the surface of the route memberthat faces the molten resin, and a method by which the air layer isformed by forming the route member as a porous body and feeding the airinto the route member, and ejecting the air from the surface thereof canbe employed.

Any member from amongst a rod-shaped guide member that passes throughand guides the cylindrical molten resin extruded from an extruder, athroat member that guides the molten resin that is extruded from anextruder and cut to the fixed length into a female mold, a resinconveying member that receives the molten resin extruded from theextruder, cuts the molten resin to a predetermined length, and conveysthe molten resin to a position above a female mold, and a female moldfor compression molding, or all these members are preferred as the routemembers to be imparted with a molten resin adhesion preventing actionwith the molten resin adhesion preventing means.

A device for feeding a molten resin in accordance with the presentinvention that resolves the above-described problems is a device forfeeding a molten resin that feeds a molten resin to a molding apparatus,the device comprising molten resin adhesion preventing means forpreventing the molten resin from adhering to a route member positionedin a route through which the molten resin passes prior to molding.

The molten resin adhesion preventing means can be configured ofvibration imparting means for imparting vibrations to the route member.Further, the molten resin adhesion preventing means can comprise meansfor feeding the air into the route member and means for ejecting the airthat has been fed into the route member onto a surface on the sidefacing the molten resin, and the ejection of the air from the inside canform an air layer on the surface on the side of the route member thatfaces the molten resin. The molten resin adhesion preventing means cancomprise means for forming an air flow that flows along a surface of theroute member that faces the molten resin, and the air layer can beformed on the surface of the route member by the air flow. Furthermore,the route member employing the molten resin adhesion preventing means isany from amongst a rod-shaped guide member that passes through andguides the cylindrical molten resin extruded from an extruder, a throatmember that guides the molten resin that is extruded from an extruderand cut to the fixed length into a female mold, a female mold forcompression molding, and a resin conveying member that receives themolten resin extruded from the extruder, cuts the molten resin to apredetermined length, and conveys the molten resin to a position above afemale mold.

Furthermore, in a method for manufacturing a molded article inaccordance with the present invention, a molten resin is fed to a moldby any method of the methods described in claims 1 to 8 and the moldedarticle is manufactured by compression molding the molten resin. Thismanufacturing method can be advantageously applied to manufacturing aspout member of a container, a preform for a container, and a containerlid.

Effect of the Invention

With the method and device for feeding a molten resin in accordance withthe present invention, sliding properties of the molten resin that isfed into a mold are improved and the molten resin can be reliablyprevented from adhering to route members positioned in the feed route ofthe molten resin by imparting a molten resin adhesion preventing actionsuch as vibrations or air layer formation with the molten resin adhesionpreventing means to the route members present within the route from thedie head to a position where the molten resin is seated in the mold. Asa result, the molten resin can be fed accurately with a stable passagetime and without a feed timing delay, alignment accuracy of the moltenresin inside the mold can be increased, the posture of the molten resininside the cavity can be stabilized, deformation of the molten resin canbe reduced, the shape thereof can be stabilized, and good moldedarticles can be obtained with good efficiency. As a result, the timerequired to feed the molten resin into the mold can be shortened and theproductivity can be increased. Furthermore, the molded articles obtainedby compression molding using the above-described feeding method andfeeding apparatus have a uniform thickness of resin, and in the case ofmultilayer resins, a fixed layer thickness can be ensured with goodstability and good compression molded articles can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view illustrating an arrangement of the firstembodiment of the molding apparatus employing the method and device forfeeding a molten resin in accordance with the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a mold forcompression molding that employs the present invention.

FIGS. 3A to 3D is a general cross-sectional view of a compressionmolding apparatus for each step of a process for feeding a molten resininto the mold shown in FIG. 2 by a method for feeding a molten resinthat is an embodiment of the present invention.

FIG. 4A is a general cross-sectional view of a compression moldingapparatus of another embodiment of the present invention, FIG. 4B is anenlarged view of the A portion.

FIG. 5A is a general cross-sectional view illustrating the state inwhich the feed of a molding resin is started to a compression moldingapparatus of another embodiment of the present invention, FIG. 5B is ageneral cross-sectional view illustrating a state in which the moltenresin is seated in a female mold.

FIG. 6A is a general cross-sectional view illustrating the state inwhich the feed of a molding resin is started to a compression moldingapparatus of another embodiment of the present invention, FIG. 6B is ageneral cross-sectional view illustrating a state in which the moltenresin is seated in a female mold.

FIG. 7 is a general cross-sectional view of route members illustrating amethod for feeding a molten resin to a molding apparatus that is anotherembodiment of the present invention.

FIGS. 8A to 8E is an explanatory drawing illustrating an operation stateof a resin conveying member, FIG. 8A is a cross-sectional viewillustrating a feed state of the molten resin from the die head, FIGS.8B to 8D are plan views illustrating the states in which the moltenresin is held, FIG. 8E is a cross-sectional view illustrating the statein which the molten resin is held.

FIG. 9 is a cross-sectional view of a throat portion of the moldingapparatus of another embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating the air discharge stateof the throat portion.

FIG. 11 is a cross-sectional view of a throat portion of the moldingapparatus of yet another embodiment of the present invention.

FIGS. 12A to 12C is an explanatory drawing illustrating a method formeasuring the passage time and molten resin diameter when the moltenresin falls down from the throat portion.

FIG. 13 is a graph illustrating the spread in passage time of the moltenresin falling down from the throat portion.

FIG. 14 is a graph illustrating the spread in diameter of the moltenresin falling down from the throat portion.

EXPLANATION OF LETTERS OR NUMERALS

1 compression molding apparatus

2 turret

3 mold

6 hollow support rod

7, 63 female mold

10, 40, 50 molten resin guide pin

11 base portion

12 spring

15 multilayer molten resin extrusion device

17, 60 die head

20 single-layer molten resin extrusion device

25 molten resin

27 vibration imparting apparatus

28, 73 vibrator

30 air feed nozzle

31, 44 nozzle insertion port

32, 89 air chamber

41 air passage

42 air blow-out port

45 air feed tube

46 air feed nozzle

61 resin conveying member

62, 70, 85 throat member

64 cavity

65 body

66 clamp piece

67 actuator

71 throat portion

74 annular groove

75 air pool

76, 90 compressed air feed port

81, 87 throat member body

82, 92 ultrasonic oscillator

86 throat portion

88 sleeve

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described in greaterdetail with reference to the appended drawings.

FIG. 1 is a schematic plan view illustrating an embodiment of a moldingdevice that employs the method and device for feeding a molten resin inaccordance with the present invention. This embodiment illustrates thecase in which a spout having a multilayer structure is formed from amolten resin that is a combination of a single-layer molten resin and amultilayer molten resin extruded from a mold of an extruder.

In FIG. 1, the reference numeral 1 stands for a compression moldingmachine. In the present embodiment, this is a rotary-type compressionmolding machine in which a plurality of molds 3 are disposed with apredetermined pitch on the outer periphery of a turret 2. As the turret2 rotates, each mold 3 successively passes by a multilayer molten resinfeed station A, a first vibration imparting station B, a single-layermolten resin feed station C, a second vibration imparting station D, acompression molding station E, and a secondary processing transferstation F, wherein a spout having a multilayer structure is formed via amultilayer molten resin feed process, a first vibration impartingprocess, a single-layer molten resin feed process, a second vibrationimparting process, a compression molding process, and a secondaryprocessing transfer process in respective stations. However, the moldedarticle in the below-described embodiments is not limited to the spout,a variety of molded articles can be molded, and the processes used formolding are not limited to the above-described processes. Furthermore,even if the parts of the same shape are molded, the molten resin feedprocesses are different in the cases where the part is molded only froma single-layer molten resin, only a multilayer molten resin, and acombination of a multilayer molten resin and a single-layer moltenresin, as in the above-described embodiment. For example, when a part ismolded only from a single-layer molten resin or a multilayer moltenresin, only one resin feed process is sufficient, and the secondvibration imparting process becomes also unnecessary.

FIG. 2 shows a schematic cross-sectional structure of the mold 3 forcompression molding of the present embodiment. As shown in the figure,the mold is an assembly of a female mold (cavity mold) 7 that issupported at the upper end section of a hollow support rod 6 that issupported at a turret body 5 and a male mold (core mold) 8 disposedopposite the female mold so that the male mold is free to move in theup-down direction. A molten resin guide pin 10 that extends along acentral axis inside the cavity of the female core and passes through anupper end wall 9 of the hollow support rod 6 is provided inside thehollow support rod so that the molten resin guide pin can move in theaxial direction. The molten resin guide pin 10 is a rod-shaped guidemember constituting a route member. A spring 12 is provided between abase portion 11 of the molten resin guide pin and a lower section of thesupport rod 6, and a predetermined spring force is applied to the moltenresin guide pin 10 so that the pin protrudes into the cavity. The moltenresin guide pin 10 guides the annular molten resin that was extrudedfrom the die head so that the molten resin is accurately seated on thefemale mold. The molten resin descends along the molten resin guide pin,whereby the resin is aligned and accurately and concentrically placedinside the cavity. The reference numeral 13 stands for a mold lockmechanism that restricts an outer peripherally section of the femalemold configured of split mold, so that the female mold does not openduring compression molding. In the present embodiment, the mold lockmechanism is provided so that it can be shifted between a position inwhich the mold (female mold) is restricted to a position in which it isreleased by an appropriate lifting means (not shown in the figures). Themold 3 is changed according to the shape and type of the molded articleand no specific limitation is placed on the structure of the mold. Awell-known mold can be appropriately employed, and the presentembodiment is applied to the case in which the mold has a molten resinguide pin that passes through the female mold.

In a multilayer molten resin feed station A, a multilayer resinextrusion device 15 is disposed as shown in FIG. 1. In the embodimentshown in the figure, the multilayer resin extrusion device 15 comprisesthree resin feeders 16-1, 16-2, 16-3, and three layered resin arelaminated in the radial direction and annularly extruded in a moltenstate from the die head 17. Further, a single-layer molten resinextrusion device 20 disposed in a single-layer molten resin feed stationC comprises one resin feeder 21 and a single-layer die head 22, suchthat the resin fed from the single resin feeder 21 is extruded from thedie head 22 and the single-layer molten resin is fed on the multilayermolten resin. Further, in the present embodiment, the multilayer moltenresin feed station A and the single-layer resin feed station C areprovided separately, but the molten resin feed stations and thebelow-described vibration imparting station may be provided in onelocation, provided that the multilayer molten resin and the single-layermolten resin are continuously extruded with a single extrusion devicefor example, as has been earlier suggested by the applicant (JapanesePublication of Patent Application No. 2004-314336).

In the molding apparatus having the above-described configuration, theroute members positioned in a route through which the molten resinextruded from the die head of the extrusion device moves till the resinis seated on the female mold include the molten resin guide pin 10 andthe inner peripheral surface of the female mold from the inlet port ofthe female mold to the zone where the molten resin is seated on thebottom portion. Therefore, provided that the resin does not adhere tothese route members and is not affected thereby, the resin can seataccurately inside the female mold. For this reason, in the presentembodiment, in order to prevent the molten resin from adhering to themolten resin guide pin 10, a first vibration imparting station B and asecond vibration imparting station D are installed and the molten resinguide pin is provided with the following means.

Vibration imparting means that cause the molten resin guide pin 10 tovibrate are provided in the first vibration imparting station B and thesecond vibration imparting station D in order to prevent the moltenresin from adhering to the route members located in the path thereof, inparticular the molten resin guide pin 10, thereby ensuring a smooth fallof the molten resin, preventing the molten resin from falling obliquelyor sticking to the route members, and shortening the fall time. Thevibration imparting means are the most important specific features ofthe present embodiment. Because the vibration imparting means disposedin the first vibration imparting station B and the second vibrationimparting station D can have the same structure, only the vibrationimparting device disposed in the first vibration imparting station Bwill be explained below.

A vibration imparting device 27 that imparts vibrations to the moltenresin guide pin 10 comprises a vibrator 28 protruding downward so thatit can move in the vertical direction, as shown in FIGS. 3C to 3D, andis so configured that by hitting the head section of the molten resinguide pin 10 with the vibrator at the predetermined frequency by meansof an appropriate vibration generator, such as an ultrasound generator,the molten resin guide pin 10 is subjected to micro-vibrations by anelastic action of the spring 12. As a result, the molten resin isprevented from adhering to the molten resin guide pin 10, and the moltenresin 25 can be accurately and smoothly, without inclination, seated onthe central section of the female mold.

FIGS. 3A to 3D is a process diagram illustrating how a molten resin isfed into the female mold by employing the molten resin prevention meansof the above-described configuration. FIGS. 3A to 3B illustrate a statein which the molten resin 25 is fed from the die head 17 in themultilayer molten resin feed station A, while being fitted into themolten resin guide pin 10, and FIG. 3B illustrates a state in which themolten resin is cut and the process of feeding the resin from the diehead is completed. FIGS. 3C to 3D illustrate a vibration impartingprocess in the first vibration imparting station B. In the multilayermolten resin feed station A, the annular molten resin 25 that wasextruded from the die head 17 is cut to the predetermined length and fedinto the molten resin guide pin 10 that protrudes into the centralportion of the female mold [FIGS. 3A to 3B]. Once the first vibrationimparting station B is reached, the vibration imparting device islowered and the vibrator 28 that oscillates at a predetermined frequencyis brought into contact with the top section of the molten resin guidepin and the guide pin is subjected to micro-vibrations. As a result, themolten resin 25 is prevented from adhering to the molten resin guidepin. Furthermore, the molten resin 25 falls smoothly along the moltenresin guide pin and is accurately seated on the predetermined positionof the female mold [FIG. 3D]. The mold 3 is then moved to thesingle-layer molten resin feed station C, a single-layer molten resin isfed, and vibrations are applied to the molten resin guide pin in thesecond vibration imparting station D in the same manner as describedabove. As a result, the single-layer molten resin smoothly falls downand assumes a state in which it is placed over the multilayer moltenresin 25. By feeding the molten resins into the female mold in theabove-described manner, the molten resin can be accurately positionedand seated inside the female mold and accurately compression molded inthe compression station.

FIGS. 4A to 4B shows another embodiment of the vibration imparting meansfor imparting vibrations to the molten resin guide pin 10. In each ofthe below-described embodiments, only the parts that differ from thoseof the first embodiment will be explained, and the identical parts willbe assigned with identical reference symbols and the explanation thereofwill be omitted.

The present embodiment relates to the structure in which the moltenresin guide pin 10 is subjected to micro-vibrations by air. FIG. 4Bshows the main components on an enlarged scale. As shown in the figure,an insertion port 31 for fitting an air feed nozzle 30 provided at thedistal end portion of an air feed tube 29 is provided in a base portion11 of the molten resin guide pin 10 fitted into the central portion ofthe hollow support rod 6 of each mold, the insertion port 31 is linkedto an air chamber 32 formed in the upper surface of the base portion 11opposite the upper end wall 9 of the hollow support rod, and air iscontinuously or intermittently fed from the air feed nozzle 30 into theair chamber 32, whereby the base portion 11 is caused to oscillate by apiston action under the effect of the air pressure and elastic pressureof the spring 12, and the molten resin guide pin 10 micro-oscillates upand down according to the dynamic relationship between the air pressureand the elastic force. As a result, the molten resin that was fed fromthe die head so as to mate with the molten resin guide pin 10 isprevented from adhering to the molten resin guide pin 10, smoothly fallsdown to the predetermined position of the female mold, and can beaccurately seated therein, without displacement. In the presentembodiment, because the vibration imparting means of the molten resinguide pin 10 is provided in each mold and moves integrally with themold, vibrations can be provided as the mold moves and the specialvibration imparting station B of the above-described embodiments isunnecessary. Therefore, the interval from the time at which the moltenresin is fed to the start of the compression molding process can beshortened.

FIG. 5 illustrates yet another embodiment of the present invention.

In the present embodiment, an air layer is formed, instead of theabove-described vibration imparting means, on the surface of the moltenresin guide pin as means for preventing the adhesion of molten resin,and this layer prevents the molten resin from adhering to the surface ofthe molten resin guide pin. As shown on an enlarged scale in FIG. 5, anair passage 41 is formed along the axial line in a molten resin guidepin 40, a large number of air blow-out holes 42 extending from the airpassage to the outer peripheral surface of the molten resin guide pinare formed so as to be almost uniformly distributed at the outerperipheral surface, a nozzle insertion port 44 linked to the air passage41 is formed in a base portion 43 of the molten resin guide pin, and anair feed nozzle 46 of the air feed pipe 45 is inserted into theinsertion port 44. By employing the molten resin guide pin of theabove-described configuration, the air is blown out and air layer isformed on the outer peripheral surface of the molten resin guide pin.Therefore, the molten resin is prevented from adhering to the moltenresin guide pin, smoothly falls down under the air bearing action, andcan be accurately seated.

In the embodiment shown in FIGS. 5A and 5B, the molten resin guide pin40 is formed by the usual metal member and a large number of airblow-out holes linked to an air passage of the central portion areformed in the outer peripheral portion of the metal member, but byforming the molten resin guide pin from a porous material, a uniform airlayer can be formed from the outer peripheral portion of the moltenresin guide pin, without forming the above-described air blow-out holes,and the molten resin guide pin can be easily manufactured.

FIGS. 6A to 6B illustrates yet another embodiment in which an air layeris formed as the molten resin adhesion preventing means on the surfaceof the molten resin guide pin. Similarly to the embodiment illustratedby FIGS. 5A to 5B, process components equivalent to the embodiment shownin FIGS. 4A to 4B are shown on an enlarged scale.

In the present embodiment, means for forming the air layer on thesurface of a molten resin guide pin 50 is configured so that the air isblown out from the base portion toward the upper portion of the moltenresin guide pin along the outer peripheral surface. Thus, in the presentembodiment, as shown on an enlarged scale in FIGS. 6A and 6B, theconfiguration is such that the compressed air is fed into a hollowportion 51 of a hollow support rod 6, this air passes by an outerperipheral portion of a base portion 52 of a molten resin guide pin 50that is fitted into the hollow portion, passes along an upper end wall 9and a bottom wall of the female mold and is discharged upward so as toenvelope the outer peripheral portion of the molten resin guide pin orthe bottom portion inside the cavity. With such a configuration, the airis ejected in the above-described manner at least from the time at whichthe resin feed from the die head is started to the time at which theresin is seated inside the female mold. As a result, an air layer isformed on the outer peripheral portion of the molten resin guide pin,and the molten resin is prevented from adhering to the molten resinguide pin and can be accurately and smoothly seated inside the femalemold.

The above-described embodiment relates to the case in which a moltenresin guide pin is provided that moves up and down inside a female moldand a molded article of a cylindrical shape is manufactured. However, inthe case where a molded article having no hollow portion passingtherethrough in the vertical direction, such as a cap, is molded, themolten resin does not assume an annular shape and, therefore, aconfiguration having the molten resin guide pin cannot be applied. Inthis case, a throat member that can be inserted between a female moldand a male mold and removed therefrom is often provided as a guide meansfor the molten resin, instead of the molten resin guide pin. Therefore,in this case, the route members from the die head to the seatinglocation include the throat member and the female mold. Furthermore, inthis case, the die head and the seat center position of the mold areoften disposed with a shift with respect to each other and theconfiguration often has a molten resin conveying member such that themolten resin fed from the die head is received by a resin conveyingmember 61, cut to the predetermined length, and conveyed to a locationabove the conveying route of the female mold. Therefore, in this case,the molten resin conveying member is added as a route member. In thebelow-described embodiment, the molten resin adhesion preventing actionis provided with a molten resin adhesion preventing means with theobject of preventing the molten resin from adhering to these routemembers.

FIG. 7 is a schematic diagram illustrating an embodiment in which theaxes of the die head and mold are shifted with respect to each other. Inthe figure, the reference numeral 60 stands for a die head, 61 standsfor a resin conveying member that receives a molten resin from the diehead, cuts the molten resin to the predetermined length, and conveys themolten resin on the movement route of the mold, 62 stands for a throatmember that is removably provided above the movement route of the femalemold, and 63 stands for a female mold. A plurality of the resinconveying members 61 are disposed with a predetermined spacing, forexample, at a rotary turret (not shown in the figures) and areintermittently driven and moved so as to pass below the die head 60 andabove the throat member 62. As shown in FIGS. 8A to 8E, the resinconveying member 61 comprises a body 65 having clamping surfaces of analmost semi-cylindrical shape for clamping and holding the molten resinthat extrude perpendicularly from the die head and a pair of clamppieces 66 that can open and close and serve as almostquarter-cylindrical clamping surfaces that face the semi-cylindricalclamping surfaces. The clamp piece 66 is opened and closed, as shown inFIGS. 8B, 8C and 8E, via an appropriate actuator 67 such as a cylinderdevice provided at the body 65. The molten resin is received in a statein which the clamp pieces 66 are open, and the molten resin is held byclosing the clamp pieces. When a molten resin cutting means for cuttingthe molten resin extruded from the die head 60 to the predeterminedlength is not provided, a cutter for cutting the molten resin isintegrally provided on the upper surface of the resin conveying member61 (such a configuration is not shown in the figures).

In the present embodiment, in the resin conveying member 61 of theabove-described configuration, a molten resin adhesion preventing meansis applied to the clamp pieces 66 in order to prevent the molten resinfrom adhering to the clamps and the drop posture of the molten resin isprevented from collapsing when the resin conveying member 61 receivesthe molten resin, moves, reaches a position directly above the throatmember 62 and drops the molten resin held thereby onto the throatmember.

As the molten resin adhesion preventing means, in the presentembodiment, at least a pair of the clamp pieces 66, 66 are configured sothat they can be vibrated by an appropriate vibration generating meanssuch as a piezoelectric element (not shown in the figure), and bycausing the vibrations of the clamp pieces when the clamp pieces aremoved to a position above the throat member 62 and opened, whereby themolten resin is prevented from sticking to the clamp pieces and theposture of the molten resin is prevented from collapsing, and the moltenresin falls into a throat 71 of the throat member in a correct posture.It would be even more effective to provide a vibration generation meansat the body 65 having the semi-cylindrical clamping surfaces, ratherthan only on the clamp pieces, and simultaneously cause the vibrationsof the body when the molten resin falls in.

In the above-described embodiment, at least a pair of claim pieces 66,66 could be vibrated, but instead of using the vibration generationmeans, an air layer can be formed on the clamping surfaces of the clamppieces for the molten resin in order to prevent the molten resin fromadhering to the clamp pieces. For this purpose, the clamp piecesthemselves are formed from a porous material and compressed air is fedinto the clamp pieces, whereby the air is blown out from the innersurface onto the entire clamping surface and the air layer is formed.With the configuration in which the feed of the air into the clamppieces can be appropriately controlled, the air can be fed only when themolten resin is separated, without forming the air layer when the moltenresin is held. In the present embodiment, not only the clamp pieces, butalso the body 65 may be formed from a porous material to form the airlayer on the clamping surfaces.

Further, if necessary, the molten resin adhesion preventing means can bealso provided at the throat member 62 and female mold 63. In theembodiment shown in FIG. 7, a vibration imparting means that causes thethroat member 62 and the female mold 63 to vibrate is provided as themolten resin adhesion preventing means also on the throat member 62 andthe female mold 63. FIG. 7 shows an embodiment in which an ultrasonicoscillator such as a piezoelectric element is used as the vibrationinducing means for the throat member to induce ultrasonic oscillations.In the throat member 62 of the present embodiment, an ultrasonicoscillator 82 comprising a piezoelectric element is appropriatelyattached to the throat member body 81, the throat member is caused tooscillate ultrasonically by an electrostriction action of thepiezoelectric element, and the molten resin 55 is prevented fromadhesion.

Further, in the present embodiment, as shown in FIG. 7, theconfiguration is such that an ultrasonic oscillator 92 such as apiezoelectric element is attached to the appropriate location of thefemale mold 63 for compression molding, and the female mold is caused tooscillate ultrasonically because of oscillations of the ultrasonicoscillator. By causing the female mold to oscillate before the moltenresin 55 is seated on the cavity 64, the molten resin can be preventedfrom adhering to the female mold in the feeding process before the resinis seated on the female mold and the molten resin can be accuratelyseated. In the figure, the reference numeral 64 stands for a cavity, and68 stands for a cooling water passage.

FIG. 9 and FIG. 10 illustrate an embodiment in which another means isprovided at the throat member as means for preventing the molten resinfrom adhering to the throat member. A throat member 70 of the presentembodiment is a combination of a throat member body 72 through whichpasses a throat 71 that serves to pass a molten resin 55 in the centralportion thereof and a ring-shaped vibrator 73. The vibrator 73 is fittedso that it can vibrate up and down in an annular groove 74 formed fromthe outer peripheral surface of a throat member body 72. The vibrator 73is formed to be thinner than the width (height in the axial direction)of the annular groove 74, an air pool 75 with an open upper end isformed in the upper surface of the vibrator, a compressed air feed port76 is formed so that the compressed air can be fed from the outside intothe air pool 75, and a compressed air feed pipe (not shown in thefigure) is attached to the compressed air feed port 76. A spring 77 isprovided between the lower surface of the vibrator 73 and the throatmember body 72, and the upper surface of the vibrator 73 is brought intointimate contact with the upper surface of the annular groove 74 andimpelled so as to close the opening of the air pool 75. The throat 71does not necessarily have a cylindrical cross section, and the designcan be changed arbitrarily, for example, so that the throat has afunnel-like or a shape corresponding to the cross-sectional shape of thelargest portion of the molten resin.

The throat member 70 of the present embodiment has the above-describedconfiguration, and when the compressed air is fed from the state shownin FIG. 9 to the compressed air feed port 76, the internal pressure ofthe air pool 75 rises and the vibrator 73 is pushed down against theforce of the spring 77 and assumes a state shown in FIG. 10. When such astate is assumed, as shown in the figure, the gap between the air pool75 and the upper wall surface 78 of the annular groove 74 increases, andthe compressed air located inside the air pool is released to theoutside. As a result, the pressure in the air pool 75 decreases.Accordingly, the vibrator is raised by the repulsion of the spring andagain assumes the state shown in FIG. 9. These operations are thereafterrepeated, that is, the cycles of increase and decrease in the airpressure in the air pool are repeated, whereby the vibrator is caused tooscillate. As a result, the upper surface of the vibrator repeatedlyhits the upper wall surface of the annular groove, the entire throatmember 70 oscillates, the molten resin 55 passing through the throatportion 71 is prevented from adhering to the inner peripheral surface ofthe throat portion, and the molten resin smoothly falls down.

FIG. 11 illustrates an embodiment in which an air layer is formed on thethroat surface as means for preventing the molten resin from adhering tothe throat member. A throat member 85 of the present embodiment has athroat 86 passing through the central portion thereof, in the samemanner as in the above-described embodiment, but the inner peripheralwall surface of the throat is formed by a sleeve 88 made from a porousmaterial. Thus, in the present embodiment, the throat member 85comprises a throat member body 87 formed from the usual metal materialand a sleeve 88 formed from a porous material and tightly mated with thethroat member body. The sleeve 88 serves as a throat that guides themolten resin. An air chamber 89 is formed in the tight mating positionof the throat member body 87 and the sleeve 88, and a compressed airfeed port 90 for feeding the compressed air from the outside is linkedto the air chamber 89.

In the throat member 85 of the present embodiment that has theabove-described configuration, an air layer is formed by blowing the airfrom the air chamber 89 onto the inner peripheral surface of the sleeve88 constituting the throat, and the molten resin that passes through thethroat 86 can be effectively caused to fall down into the female mold,without adhering to the throat. By providing the throat member with theabove-described means for preventing the molten resin from adhesion, astable drop of the molten resin can be ensured even if the throatdiameter is decreased. For the molten resin to have a good posture infalling, it is desired that the throat diameter be as small as possiblewith respect to the molten resin diameter, but if the throat diameter isdecreased, the molten resin adheres to the throat and cannot fallsmoothly. Therefore, the conventional configurations had to have a largethroat diameter, but in this case the molten resin could not maintaingood posture in falling.

Various embodiments of molten resin adhesion preventing means in themethod and device for feeding a molten resin in accordance with thepresent invention were described above, but these molten resin adhesionpreventing means are not necessarily required to be provided on all theroute members such as a rod-shaped guide member (molten resin guidepin), a resin conveying member, a throat member, or a female mold, andan appropriate combination of such means may be employed according tothe molded article and the like. Further, the molten resin adhesionpreventing means are not limited to the above-described embodiments.

The above-described method and device for feeding a molten resin inaccordance with the present invention can be applied to manufacturing avariety of molded articles, but it is especially suitable forcompression molding the spout members of containers, preforms forcontainers, or container lids. In particular, when such molded articleshaving a multilayer structure are manufactured, the molten resin can becompression molded after being accurately seated inside the female mold.Therefore, the displacement of layers and changes in the layer thicknesscan be prevented and molding can be effectively performed.

EXAMPLES Example 1

The effect of vibrations on the fall of a molten resin in a device forfeeding a molten resin of the embodiment shown in FIG. 2 was studiedwith respect to the case in which the molten resin guide pin wasvibrated (Example) and the case where the guide pin was not vibrated(Comparative Example). The seating state of the molten resin was studiedwith respect to the case of the Example in which the molten resin wascaused to fall down into a female mold, while the vibrations with afrequency of 258 Hz and an amplitude of 1 mm were applied for 0.2 sec tothe molten resin guide pin, and the Comparative Example in which themolten resin was caused to fall down into the female mold, withoutsubjecting the molten resin guide pin to vibrations. The test wasconducted 50 times. The results demonstrated that in the Example, themolten resin was accurately seated inside the female mold in all thetests and no fall defects were observed. By contrast, in the ComparativeExample, the seating state was poor in 25 of 50 tests and fall defectswere observed in 50% of cases. The tests have thus confirmed thatvibrating the molten resin guide pin is very effective for accuratelyseating the molten resin.

Example 2

In the configuration shown in FIG. 7 in which a molten resin fell into afemale mold via a throat member, the time required for a molten resin topass from the lower end of a throat member 100 to a position about 16 mmbelow the lower end was measured, as shown in FIG. 12A, with a lasercontour measurement device 101 with respect to the case in which themolten resin was continuously passed 340 times through a throat and thethroat member was vibrated (Example) and the case in which the throatmember was not vibrated (Comparative Example). In the measurements, theinterval from the time at which the distal end of the molten resincrossed a laser beam emitted from a laser generator 102 to the time atwhich the rear end of the molten resin crossed the beam was measured. Agraph shown in FIG. 13 was obtained based on the measurement results.The graph clearly shows that when the throat was vibrated, the intervalwas within 0.07 to 0.08 sec in 50% or more tests, and the intervalswithin a range of 0.11 to 0.12 sec in which 0.12 sec was the maximuminterval took not more than 2%. It was thus confirmed that the spreadwas small, the molten resin fell down with almost uniform periods, thepassage time was stable, and practically no adhesion of molten resinoccurred inside the throat. By contrast, when the throat member was notvibrated, the fall-down time was distributed within a wide range of 0.06to 0.64 sec and the delay (adhesion) of the molten resin in the throatwas observed.

Example 3

The tilted configuration of the falling molten resin was measured byusing the laser contour measurement device identical to that of Example2 when the throat was vibrated (Example) and not vibrated (ComparativeExample). The molten resin apparently meets a certain resistance due topartial adhesion to the throat and falls in a tilted state. As shown inFIG. 12C, when the molten resin is tilted, the maximum interval sincreases, but the decreasing maximum interval s is determined toimprove the resin posture in falling. Accordingly, the tilted state ofthe molten resin was measured by measuring the maximum interval s inwhich the laser beam is crossed. A graph shown in FIG. 14 represents theresults obtained. The graph clearly shows that in the Example, almost60% of the molten resin samples are distributed within a range ofmaximum diameter of 25.5 to 26 mm, and the molten resin can be confirmedto fall in a comparatively uniform stable state. By contrast, in theComparative Example, the maximum diameter of the molten resin variedsignificantly and was unstable.

Industrial Applicability

The present invention can be applied as a method for feeding a moltenresin that is suitable for feeding a molten resin to a molding apparatusfor molding a variety of molded articles such as preforms, spoutmembers, and container lids, this method making it possible to preventthe molten resin extruded from a die head from adhering to memberslocated in a route to the seating zone of a female mold, to stabilizethe molten resin passage time, molten resin diameter, and posture insidethe cavity, and to seat the molten resin accurately inside the cavity,whereby even molded articles with a multilayer structure can be moldedeffectively without a spread in the intermediate resin layers. Thepresent invention can be also applied as an apparatus for feeding amolded resin and as a method for manufacturing a molded article with themolten resin that was thus fed.

1. A method for feeding a molten resin by which a molten resin isextruded from a die head fed to a compression molding apparatus disposedat a distance from the die head, wherein a route member, positioned in aroute through which the molten resin passes after extrusion from the diehead and prior to seating on a mold of the compression moldingapparatus, is subjected to a molten resin adhesion preventing action bya molten resin adhesion preventing means, whereby the molten resin isfed to the compression molding apparatus, while being prevented fromadhering to the route member, wherein the molten resin adhesionpreventing means imparts vibrations to the route member.
 2. The methodfor feeding a molten resin according to claim 1, wherein the routemember is a throat member the throat member guides the molten resin to amold after the molten resin is extruded and cut to a fixed size.
 3. Themethod for feeding a molten resin according to claim 1, wherein theroute member is a resin conveying member that receives the molten resinextruded from the extruder, cuts the molten resin to a predeterminedlength, and conveys the molten resin to a position above a female mold.4. A device for feeding a molten resin that feeds a molten resinextruded from a die head to a compression molding apparatus disposed ata distance from the die head, the device comprising molten resinadhesion preventing means imparting a molten resin adhesion preventingaction to a route member for preventing the molten resin from adheringto the route member positioned in a route through which the molten resinpasses after extrusion from the die head and prior to seating on a moldof the compression molding apparatus, wherein the molten resin adhesionpreventing means is vibration imparting means for imparting vibrationsto the route member.
 5. The device for feeding a molten resin accordingto claim 4, wherein the route member is a throat member for guiding themolten resin that is extruded from an extruder and cut to a fixed sizeto a mold.
 6. The device for feeding a molten resin according to claim4, wherein the route member is a resin conveying member that receivesthe molten resin extruded from the extruder, cuts the molten resin to apredetermined length, and conveys the molten resin to a position above afemale mold.
 7. A method for manufacturing a molded article, wherein amolten resin is fed to a mold by any of the methods described in claims1 to 3, and the molded article is manufactured by compression moldingthe molten resin.
 8. The method for manufacturing a molded articleaccording to claim 7, wherein the molded article is a preform for acontainer.
 9. The method for manufacturing a molded article according toclaim 7, wherein the molded article is a container lid.